SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice
Accurate modeling of cryospheric surface albedo is essential for our understanding of climate change as snow and ice surfaces regulate the global radiative budget and sea-level through their albedo and mass balance. Although significant progress has been made using physical principles to represent t...
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Copernicus Publications
2022
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Online Access: | https://doi.org/10.5194/tc-16-1197-2022 https://doaj.org/article/a93a2207819c4e5297c7f71b9ab4a77f |
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ftdoajarticles:oai:doaj.org/article:a93a2207819c4e5297c7f71b9ab4a77f 2023-05-15T18:18:55+02:00 SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice C. A. Whicker M. G. Flanner C. Dang C. S. Zender J. M. Cook A. S. Gardner 2022-04-01T00:00:00Z https://doi.org/10.5194/tc-16-1197-2022 https://doaj.org/article/a93a2207819c4e5297c7f71b9ab4a77f EN eng Copernicus Publications https://tc.copernicus.org/articles/16/1197/2022/tc-16-1197-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-1197-2022 1994-0416 1994-0424 https://doaj.org/article/a93a2207819c4e5297c7f71b9ab4a77f The Cryosphere, Vol 16, Pp 1197-1220 (2022) Environmental sciences GE1-350 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/tc-16-1197-2022 2022-12-31T04:58:33Z Accurate modeling of cryospheric surface albedo is essential for our understanding of climate change as snow and ice surfaces regulate the global radiative budget and sea-level through their albedo and mass balance. Although significant progress has been made using physical principles to represent the dynamic albedo of snow, models of glacier ice albedo tend to be heavily parameterized and not explicitly connected with physical properties that govern albedo, such as the number and size of air bubbles, specific surface area (SSA), presence of abiotic and biotic light absorbing constituents (LACs), and characteristics of any overlying snow. Here, we introduce SNICAR-ADv4, an extension of the multi-layer two-stream delta-Eddington radiative transfer model with the adding–doubling solver that has been previously applied to represent snow and sea-ice spectral albedo. SNICAR-ADv4 treats spectrally resolved Fresnel reflectance and transmittance between overlying snow and higher-density glacier ice, scattering by air bubbles of varying sizes, and numerous types of LACs. SNICAR-ADv4 simulates a wide range of clean snow and ice broadband albedo (BBA), ranging from 0.88 for (30 µ m) fine-grain snow to 0.03 for bare and bubble-free ice under direct light. Our results indicate that representing ice with a density of 650 kg m −3 as snow with no refractive Fresnel layer, as done previously, generally overestimates the BBA by an average of 0.058. However, because most naturally occurring ice surfaces are roughened “white ice”, we recommend modeling a thin snow layer over bare ice simulations. We find optimal agreement with measurements by representing cryospheric media with densities less than 650 kg m −3 as snow and larger-density media as bubbly ice with a Fresnel layer. SNICAR-ADv4 also simulates the non-linear albedo impacts from LACs with changing ice SSA, with peak impact per unit mass of LACs near SSAs of 0.1–0.01 m 2 kg −1 . For bare, bubble-free ice, LACs actually increase the albedo. SNICAR-ADv4 represents smooth ... Article in Journal/Newspaper Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles The Cryosphere 16 4 1197 1220 |
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Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
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Environmental sciences GE1-350 Geology QE1-996.5 C. A. Whicker M. G. Flanner C. Dang C. S. Zender J. M. Cook A. S. Gardner SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Accurate modeling of cryospheric surface albedo is essential for our understanding of climate change as snow and ice surfaces regulate the global radiative budget and sea-level through their albedo and mass balance. Although significant progress has been made using physical principles to represent the dynamic albedo of snow, models of glacier ice albedo tend to be heavily parameterized and not explicitly connected with physical properties that govern albedo, such as the number and size of air bubbles, specific surface area (SSA), presence of abiotic and biotic light absorbing constituents (LACs), and characteristics of any overlying snow. Here, we introduce SNICAR-ADv4, an extension of the multi-layer two-stream delta-Eddington radiative transfer model with the adding–doubling solver that has been previously applied to represent snow and sea-ice spectral albedo. SNICAR-ADv4 treats spectrally resolved Fresnel reflectance and transmittance between overlying snow and higher-density glacier ice, scattering by air bubbles of varying sizes, and numerous types of LACs. SNICAR-ADv4 simulates a wide range of clean snow and ice broadband albedo (BBA), ranging from 0.88 for (30 µ m) fine-grain snow to 0.03 for bare and bubble-free ice under direct light. Our results indicate that representing ice with a density of 650 kg m −3 as snow with no refractive Fresnel layer, as done previously, generally overestimates the BBA by an average of 0.058. However, because most naturally occurring ice surfaces are roughened “white ice”, we recommend modeling a thin snow layer over bare ice simulations. We find optimal agreement with measurements by representing cryospheric media with densities less than 650 kg m −3 as snow and larger-density media as bubbly ice with a Fresnel layer. SNICAR-ADv4 also simulates the non-linear albedo impacts from LACs with changing ice SSA, with peak impact per unit mass of LACs near SSAs of 0.1–0.01 m 2 kg −1 . For bare, bubble-free ice, LACs actually increase the albedo. SNICAR-ADv4 represents smooth ... |
format |
Article in Journal/Newspaper |
author |
C. A. Whicker M. G. Flanner C. Dang C. S. Zender J. M. Cook A. S. Gardner |
author_facet |
C. A. Whicker M. G. Flanner C. Dang C. S. Zender J. M. Cook A. S. Gardner |
author_sort |
C. A. Whicker |
title |
SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
title_short |
SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
title_full |
SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
title_fullStr |
SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
title_full_unstemmed |
SNICAR-ADv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
title_sort |
snicar-adv4: a physically based radiative transfer model to represent the spectral albedo of glacier ice |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-1197-2022 https://doaj.org/article/a93a2207819c4e5297c7f71b9ab4a77f |
genre |
Sea ice The Cryosphere |
genre_facet |
Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 16, Pp 1197-1220 (2022) |
op_relation |
https://tc.copernicus.org/articles/16/1197/2022/tc-16-1197-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-1197-2022 1994-0416 1994-0424 https://doaj.org/article/a93a2207819c4e5297c7f71b9ab4a77f |
op_doi |
https://doi.org/10.5194/tc-16-1197-2022 |
container_title |
The Cryosphere |
container_volume |
16 |
container_issue |
4 |
container_start_page |
1197 |
op_container_end_page |
1220 |
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1766195680044384256 |